Thomas arrives in southern India?There is a substantial literature. I have usually followed the two balanced and generally objective books by L. W. Brown and Stephen Neill. Some of the other general works are listed in Notes for Chapter 16.Brown, L. W. The Indian Christians of St. Thomas (1956).
Neill, Stephen. A History of Christianity in India (1984).

Early history of KeralaL D. Barnett, "The Early History of Southern India," Cambridge Ancient History , vol. 5, ch. 24;
K. A. Nilakanta Sastri, A History of South India (3rd ed. 1966) 1-16, 78-98, 115-38, 428;
George Woodcock, Kerala: A Portrait of the Malabar Coast (1967) 65-111.